Dr. Dorsey is pursuing a career as an independent researcher focused on the prevention of obesity in children. As a pediatric resident at the Children's Hospital of New York, from 1998 to 2001, Dr. Dorsey realized that her limited knowledge of nutrition, physical activity, and other physiological processes that determine weight gain left her ill prepared to help her overweight patients. Equally troubling were the paucity of research that could guide clinical practice and the absence of effective interventions for the prevention of obesity. This clinical need sparked her interest in conducting research to improve the clinician's ability to address the behavioral, physiological, and environmental factors that lead to obesity, and improve efforts at obesity prevention in children. Dr. Dorsey's training and research experiences in the Robert Wood Johnson Clinical Scholars Program and the Investigative Medicine Program (a doctoral program at Yale School of Medicine) from 2001 to 2006 provided her with a strong foundation in research methodology. As a fellow she received formal education in research study design and biostatistics as well as experience conducting research in clinical populations using direct motion monitoring with accelerometers to assess physical activity behaviors in overweight and non-overweight children. Support from this award will allow Dr. Dorsey to pursue additional training through coursework, mentorship, and research to understand how physical activity and physical fitness relate to adiposity in children. Drs. Dorsey and Krumholz have assembled a group of diverse mentors and advisors to assist her with training, the proposed research projects, and guide her career development. This mentorship team is divided into Sponsors and an Oversight Committee of advisors. Each of these individuals has expertise related to Dr. Dorsey's short-term and long-term career goals. The proposed project will be conducted across two campuses, NYORC in New York and Yale School of Medicine in New Haven. Dr. Dorsey will have a co mentor, advisors and collaborators at each site. She has been successfully working across the two campuses since 2006. Dr. Dorsey lives in New York City and travels between New York and New Haven with ease using the commuter train, meeting regularly with mentors and conducts research activities at both sites. This success will continue over the training period proposed in this application. The overall goal of the proposed research is to determine the potential utility of exercise testing and physical activity monitoring to support obesity prevention in clinical settings. This work will establish whether physical activity monitoring and exercise testing can be administered in a pediatric clinic setting and whether these tools can help clinicians identify which children in their practices are at greatest risk of obesity. Using a cross-sectional analysis, Dr. Dorsey will demonstrate how performance on exercise tests relates to directly measured physical activity levels and to clinical measures of body composition. She will use a longitudinal analysis to determine whether performance on exercise tests and/or directly measured physical activity levels predict changes in waist circumference or BMI SD values over 1-year. Study participants will be non-obese 7 - to 9- year old children with a body mass index above the 50th percentile for age and gender in order to identify early clinical indicators of increased risk of obesity in children. This research will be focused on clinical populations of Latino and African-American children living in urban centers where obesity and related co-morbid diseases such as diabetes mellitus are most prevalent. There is an urgent need to address the high prevalence of obesity in these populations, and an opportunity to increase knowledge regarding physical activity and fitness among children in whom these factors have not been well described. In the future, these results will be used to design interventions that improve obesity prevention in minority populations and in pediatric healthcare settings. The proposed project will build on Dr. Dorsey's previous research involving the use of direct motion monitoring in which she developed a novel method for analyzing motion data in 8-10-year old children. This new approach identifies bouts of vigorous physical activity, and characterizes the number of bouts children perform, their length (minutes), and their average motion intensity (counts). Dr. Dorsey also examined how these patterns relate to obesity in children. Support from this award will allow Dr. Dorsey to combine this research experience with new training in exercise physiology, assessment of body composition, social and psychological epidemiology, understanding health disparities, performance improvement in healthcare settings, and cost benefit analysis for the application of new medical technologies and treatment strategies. Ultimately she will translate these methods and tools for clinical application to improve prevention strategies for children in primary care and community settings. In five years Dr. Dorsey will be an independent researcher with substantial expertise in the assessment of the physiological and behavioral factors that promote obesity and how these factors affect children in different ways and to different degrees during their development. The research she completes in the next five to ten years will inform the design and evaluation of interventions both within clinical settings and in collaboration with larger public policy initiatives to reduce the prevalence of obesity in children.